New Members of a Class of Monomeric {Fe(NO) 2 } 10 Dinitrosyliron Complexes and a Dimeric {Fe(NO) 2 } 10 –{Fe(NO) 2 } 10 Dinitrosyliron Complex

The monomeric {Fe(NO) 2 } 10 dinitrosyliron complexes (DNICs) [K‐18‐crown‐6‐ether][(NO) 2 Fe(NC 9 H 6 ‐NH)] ( 1 ), [K‐18‐crown‐6‐ether][(NO) 2 Fe(NC 9 H 6 ‐O)] ( 2 ), and [K‐18‐crown‐6‐ether][(NO) 2 Fe(NC 9 H 6 ‐S)] ( 3 ) containing [N,NH], [N,O], and [N,S] ligations were synthesized by displacing the N , N , N′ , N′ ‐tetramethylethylenediamine (tmeda) group of {Fe(NO) 2 } 10 (tmeda)Fe(NO) 2 with quinolin‐8‐amide, quinolin‐8‐olate, and quinolin‐8‐thiolate, respectively. Anionic {Fe(NO) 2 } 10 DNICs 1 – 3 were characterized by IR, 1 H NMR, and UV/Vis spectroscopy and single‐crystal X‐ray diffraction. The binding affinity of the ligands (i.e., [NC 9 H 6 NH] – , [NC 9 H 6 O] – , and [NC 9 H 6 S] – ) toward the {Fe(NO) 2 } 10 fragment was also investigated, and ligand substitution was found to follow the order [NC 9 H 6 S] – > [NC 9 H 6 O] – > [NC 9 H 6 NH] – . Displacement of the tmeda group of (tmeda)Fe(NO) 2 by [K‐18‐crown‐6‐ether][SC 6 H 4 ‐ o ‐NH 2 ] and [PPh 4 ][SC 6 H 4 ‐ o ‐NH 2 ] afforded monomeric {Fe(NO) 2 } 10 DNIC [K‐18‐crown‐6‐ether][(NO) 2 Fe(SC 6 H 4 ‐ o ‐NH 2 )] ( 4 ) and dimeric {Fe(NO) 2 } 10 –{Fe(NO) 2 } 10 DNIC [PPh 4 ] 2 [(NO) 2 Fe(μ‐SC 6 H 4 ‐ o ‐NH 2 )] 2 ( 5 ), respectively. The function of the countercation in the formation of monomeric {Fe(NO) 2 } 10 DNIC 4 or dimeric {Fe(NO) 2 } 10 –{Fe(NO) 2 } 10 DNIC 5 was also demonstrated upon reduction of the {Fe(NO) 2 } 9 DNICs [cation][(NO) 2 Fe(SC 6 H 4 ‐ o ‐NH 2 ) 2 ] ( 6 ) {cation = K‐18‐crown‐6‐ether ( 6a ), [PPh 4 ] ( 6b )}. In contrast to the formation of thiolate‐containing {Fe(NO) 2 } 9 DNICs through nucleophilic cleavage of the bridging thiolates of Roussin's red esters, the transformation of complexes 4 and 5 into complexes 6a and 6b , respectively, in the presence of disulfide provides a new synthetic pathway for the synthesis of thiolate‐containing {Fe(NO) 2 } 9 DNICs.